Dr. Someshwar Das

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Uses of Radar & Satellite Data in the Numerical Simulation of the Monsoon Rainstorms


Deep precipitating convective systems often form over the Indian region producing anomalously high rainfall during their mature stage. Such events are generally associated with a cyclonic circulation extending from lower to the middle troposphere and a wind shear line extending from the Arabian Sea to the Bay of Bengal across the southern peninsular India or across the Indo-Gangetic plains during certain phases of the south Asian summer monsoon season. On occasions, an eastward-moving upper-level westerly trough (also known as western disturbances) interacts with the westward-moving monsoon lows at lower levels along the monsoon trough over the Indo-Gangetic plains. The two systems intensify interactively, forming a deep depression that produces heavy rainfall over the region.

In this presentation, some of the heavy rainfall events including cloudbursts that occurred over the Indian region during the past 10 years will be reviewed. Many attempts are made to simulate those events using Numerical Weather Prediction models. The cloud microphysical properties associated with the heavy rainfall episodes are studied based on observations from satellite, radar and model simulations. The skill scores and predictability of the models will be discussed.